As an inkjet head in the past, there is known a head manufactured by forming plural pressure chamber grooves in a piezoelectric member side by side and, after forming electrodes on the inner surfaces of the pressure chamber grooves, bonding a cover to crosslink plural walls that partition the pressure chamber grooves. As a substrate that holds the piezoelectric member, in general, a substrate made of alumina is used.
In the manufacturing process for the inkjet head, there is a step of forming an inclined surface of the piezoelectric member. In the step, the surface of the substrate made of alumina is also ground. Since the ground surface of the substrate made of alumina is easily smoothed compared with the piezoelectric member, it is likely that the adhesion force of plating on the ground surface of the substrate is weakened. In order to solve this problem, there is known an inkjet head in which the surface is roughed by etching to improve the adhesion force of the plating on the ground surface of the substrate. In this step, if immersion treatment with etching liquid is performed in a state in which the substrate made of alumina and the piezoelectric member are bonded, it is likely that the piezoelectric member is excessively roughed.